<?php

/*
  掌握满足单例模式的必要条件
  (1)私有的构造方法-为了防止在类外使用new关键字实例化对象
  (2)私有的成员属性-为了防止在类外引入这个存放对象的属性
  (3)私有的克隆方法-为了防止在类外通过clone成生另一个对象
  (4)公有的静态方法-为了让用户进行实例化对象的操作
 */

namespace Mysqli;

class Mysqli
{

    //私有的属性
    private static $dbcon = false;
    private $host;
    private $port;
    private $user;
    private $pass;
    private $db;
    private $charset;
    private $link;

    /**
     * 私有的构造方法
     * @param type $config
     */
    public function __construct($config = array())
    {
        $this->host = $config['host'] ? $config['host'] : 'localhost';
        $this->port = $config['port'] ? $config['port'] : '3306';
        $this->user = $config['user'] ? $config['user'] : 'root';
        $this->pass = $config['pass'] ? $config['pass'] : 'root';
        $this->db = $config['db'] ? $config['db'] : 'small2';
        $this->charset = isset($config['charset']) ? $config['charset'] : 'utf8';
        //连接数据库
        $this->db_connect();
        //选择数据库
        $this->db_usedb();
        //设置字符集
        $this->db_charset();
    }

    /**
     * 连接数据库
     * @throws \Exception
     */
    private function db_connect()
    {
        $this->link = mysqli_connect($this->host . ':' . $this->port, $this->user, $this->pass);
        if (!$this->link)
        {
            $msg = "数据库连接失败" . PHP_EOL . "错误编码:" . mysqli_errno($this->link) . PHP_EOL . "错误信息:" . mysqli_error($this->link) . PHP_EOL;
            throw new \Exception($msg);
        }
    }

    /**
     * 设置字符集
     */
    private function db_charset()
    {
        mysqli_query($this->link, "set names {$this->charset}");
    }

    /*     * 选择数据库
     * 
     */

    private function db_usedb()
    {
        mysqli_query($this->link, "use {$this->db}");
    }

    /**
     * 私有的克隆
     * @throws \Exception
     */
    private function __clone()
    {
        $msg = "clone is not allowed";
        throw new \Exception($msg);
    }

    /**
     * 公用的静态方法
     * @return type
     */
    public static function getIntance()
    {
        if (self::$dbcon == false)
        {
            self::$dbcon = new self;
        }
        return self::$dbcon;
    }

    /**
     * 执行sql语句的方法
     * @param type $sql
     * @return type
     * @throws \Exception
     */
    public function query($sql)
    {
        $res = mysqli_query($this->link, $sql);
        if (!$res)
        {
            $msg = "sql语句执行失败" . PHP_EOL . "错误编码:" . mysqli_errno($this->link) . PHP_EOL . "错误信息:" . mysqli_error($this->link) . PHP_EOL;
            throw new \Exception($msg);
        }
        return $res;
    }

    /**
     * 获得最后一条记录id
     * @return int
     */
    public function getInsertid()
    {
        return mysqli_insert_id($this->link);
    }

    /*
     * 查询某个字段
     * @param
     * @return string or int
     */

    public function getOne($sql)
    {
        $query = $this->query($sql);
        return mysqli_free_result($query);
    }

    /**
     * 获取一行记录,return array 一维数组
     * @param type $sql
     * @param type $type
     * @return type
     * @throws \Exception
     */
    public function getRow($sql, $type = "assoc")
    {
        $query = $this->query($sql);
        if (!in_array($type, array("assoc", 'array', "row")))
        {
            $msg = "mysqli_query";
            throw new \Exception($msg);
        }
        $funcname = "mysqli_fetch_" . $type;
        return $funcname($query);
    }

    /**
     * 获取一条记录,前置条件通过资源获取一条记录
     * @param type $query
     * @param type $type
     * @return type
     * @throws \Exception
     */
    public function getFormSource($query, $type = "assoc")
    {
        if (!in_array($type, array("assoc", "array", "row")))
        {
            $msg = "mysqli_query";
            throw new \Exception($msg);
        }
        $funcname = "mysqli_fetch_" . $type;
        return $funcname($query);
    }

    /**
     * 获取多条数据，二维数组
     * @param type $sql
     * @return type
     */
    public function getAll($sql)
    {
        $query = $this->query($sql);
        $list = array();
        while ($r = $this->getFormSource($query))
        {
            $list[] = $r;
        }
        return $list;
    }

    /*
     * 定义添加数据的方法
     * @param string $table 表名
     * @param string orarray $data [数据]
     * @return int 最新添加的id
     */

    public function insert($table, $data)
    {
        //遍历数组，得到每一个字段和字段的值
        $key_str = '';
        $v_str = '';
        foreach ($data as $key => $v)
        {
            if (empty($v))
            {
                $msg = "error";
                throw new \Exception($msg);
            }
            //$key的值是每一个字段s一个字段所对应的值
            $key_str .= $key . ',';
            $v_str .= "'$v',";
        }
        $key_str = trim($key_str, ',');
        $v_str = trim($v_str, ',');
        //判断数据是否为空
        $sql = "insert into $table ($key_str) values ($v_str)";
        $this->query($sql);
        //返回上一次增加操做产生ID值
        return $this->getInsertid();
    }

    /*
     * 删除一条数据方法
     * @param1 $table, $where=array('id'=>'1') 表名 条件
     * @return 受影响的行数
     */

    public function deleteOne($table, $where)
    {
        if (is_array($where))
        {
            foreach ($where as $key => $val)
            {
                $condition = $key . '=' . $val;
            }
        } else
        {
            $condition = $where;
        }
        $sql = "delete from $table where $condition";
        $this->query($sql);
        //返回受影响的行数
        return mysqli_affected_rows($this->link);
    }

    /*
     * 删除多条数据方法
     * @param1 $table, $where 表名 条件
     * @return 受影响的行数
     */

    public function deleteAll($table, $where)
    {
        if (is_array($where))
        {
            foreach ($where as $key => $val)
            {
                if (is_array($val))
                {
                    $condition = $key . ' in (' . implode(',', $val) . ')';
                } else
                {
                    $condition = $key . '=' . $val;
                }
            }
        } else
        {
            $condition = $where;
        }
        $sql = "delete from $table where $condition";
        $this->query($sql);
        //返回受影响的行数
        return mysqli_affected_rows($this->link);
    }

    /*
     * [修改操作description]
     * @param [type] $table [表名]
     * @param [type] $data [数据]
     * @param [type] $where [条件]
     * @return [type]
     */

    public function update($table, $data, $where)
    {
        //遍历数组，得到每一个字段和字段的值
        $str = '';
        foreach ($data as $key => $v)
        {
            $str .= "$key='$v',";
        }
        $str = rtrim($str, ',');
        //修改SQL语句
        $sql = "update $table set $str where $where";
        $this->query($sql);
        //返回受影响的行数
        return mysqli_affected_rows($this->link);
    }

}

?>